VOL. 3, NO. 6, June 2013 ISSN 2225-7217 ARPN Journal of Science and Technology ©2011-2013. All rights reserved. http://www.ejournalofscience.org 639 Characterization of Electro Active Polymer Composite Films Based on Gelatin and Poly 2-(3-thienyl)-ethoxy-4-butylsulfonate (PTEBS) 1 Md. Alamgir Kabir, 2 Khadiza Begam, 3* M. Mahbubur Rahman, 4 Fahmida Parvin, 5 Md. Arifur Rahman, 6 Jahid M. M. Islam, 7 Md. Abul Hossain, 8 Farid Ahmed, 9 Mubarak A. Khan 1, 2,3,7,8 Department of Physics, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh 3 School of Engineering & Information Technology, Murdoch University, Perth, Western Australia 6150, Australia 4,5,6,9 Institute of Radiation & Polymer Technology, Atomic Energy Research Establishment, Savar, Dhaka, Bangladesh *3 Corresponding Author: M. Mahbubur Rahman, mahbub235@yahoo.com ABSTRACT Composites of gelatin and polythiophene sodium poly 2-(3-thienyl)-ethoxy-4-butylsulfonate (PTEBS) were prepared by solution casting. PTEBS content in the composites were in the range of (wt.%) 0.01-0.08%. The surface morphology of the composite films was investigated by means of a scanning electron microscope (SEM). The electrical conductivity of the composites has been found to show Ohmic behavior while the dielectric characteristics show normal characteristics. The light-harvesting ability of the composite films was investigated by UV-Visible spectroscopy. Throughout the investigation it has been observed that the electrical and dielectric properties, and light harvesting efficiency of the composite films improved significantly with the incorporation of PTEBS to the pure gelatin. Keywords: Gelatin, PTEBS, surface morphology, electrical conductivity, electrical impedance, dielectric constant, optical properties. 1. INTRODUCTION The growing demand for cost-effective approach to develop raw materials for energy storage devices or organic electronics utilizing biopolymers is an important scientific and technological concern. Electro active Polymers based on biopolymers have received much attention from academics and industries because of their potential applications such as sensor, actuators, biosensor, solar materials and components in high-energy batteries [1-3]. For example biopolymers like chitin, cellulose, starch that have a wide range of applications, functioning as energy storage, [4] transport, signalling, and structural components. However, the study on the electrical and optical properties of biopolymers like gelatin has found very scant attention. Even though all the polymers are not electrically conductive, however most of them shear some intrinsic electrical properties. Their flexibility in design and compatibility with a wide range of substrates and cost- effectiveness make them appealing for use in low-cost, flexible solar cells. One way to make organic material more conductive is to add impurity atoms that donate mobile charges to their molecular host [5]. Another approach is to mix two chosen molecules carefully that exchange charge with each other and together form a crystalline, conducting solid known as charge-transfer salt [5]. This research works gives a new insight in the development of electro active composite films based gelatin and PTEBS. Gelatin is a biopolymer. It is a well-characterized protein fragment obtained by partial degradation of water insoluble collagen fiber [6] and it is relatively low cost [7]. Gelatin is a denatured collagen, undergoes thermo reversible gelation in hydrogen-bond friendly environment, when the protein concentration is higher than typically 2-3% (w/v). Many efforts have been devoted in the past to study the kinetics of gelation mechanism of this protein [7-13]. Considering the fact that this is one of the most abundantly found proteins in mammals, the importance of such studies can be hardly stressed. Gelatin, as any protein, is an optically active material in both the random coil and helical states. However, due to coherent long-range chiral ordering, helical domains rotate the plane of light polarization much more strongly than the individual chiral amino acids in the coil state. Thus, the coherent optical activity gives a direct indication of the fraction of the monomers in helical states [14]. In the work described in this paper, we have utilized the unique properties of a water-soluble, light- absorbing polythiophene polymer to fabricate electro active composite films. The idea is to take advantage of the properties of conjugated polymers (flexible, tenable, and easy to process) and incorporate the additional benefits of water solubility to have good compatibility with gelatine. In addition, the anionic side chain containing secondary amine in gelatin can promote good compatibility with PTEBS (Figures 1a and 1b). It is important to mention here that the benefits of using water as the solvent are numerous. Solvent evaporation rates have been shown to have a strong influence on film morphology and device performance [15-16] and the evaporation of water can be carefully controlled using heat. Because water is a part of the fabrication process, devices made from this polymer can show improved stability under atmospheric conditions.